Method of manufacturing carborundum filaments.



and hydrogen gases.

omen @TATESPATLHW FRANK C. THOMS, OF PITTSBURGH, PENNSYLVANIA, ..SSIGI IOR TO THE NER'NS'L LAM? COMPANY, A CORPORATION OF PENNSYLVANIA.

METHOD OF MANUFACTUTLHNG- CAR-BUBUNLOUM FILA'MENTS.

No Drawing.

Specification of Letters Patent.

itatented "31: cc. $841, 1912.

Application filed December a. 1909. Serial No. 531,358.

To all 10/1071). 1' 6 in try concern Be it known that 1', FRANK C. Trrons, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have made a new and useful Invention in ividlllbtlb' of hilanu'tati turing Carborundum l ilaments of which the following is a specification.

This invention vrelates to the method of manutacturii'lg carhorundum (at-hid of silicon) filaments for use either as heaters or glowers in second class conductor lamps or the like, or as glowers tor vacuum lamps.

Carborundum filaments have heretofore been manufactured by flashing a carbon core in an atmosphere of a mixture of hydrogen and ethylene gases and the vapors of ilicon tctrachlorid, and so far as I know, the vapors of silicon tetrachhn'id have been derived by passing the hydrogen and ethylene gases on their way to the flashing jar through a vessel or tube containing liquid silicon tetracl'ilorid. I have found that While this method may be used with some success in a laboratory, in a coun'ncrcial sense it is practically useless asthc filaments produced by it are notuniform.

An object of this invention is to produce a. commercial method for manufacturing carhorundum filaments. In carrying out my method the flashing jar which may he of any desired shape or size is rigged so that when in position it is sealed against leak which would be occasioned by the differences in pressure to which it is subjected. Within the jar, clips are arranged for holding the filaments to he treated in the electric circuit to be used. The jar, by m ans of a valved connection, is connected to a source of supply of a mixture of ethylene Another valved con nection connects the jar with the interior of a container or bottle containing liquid silicon tctrachlorid. in practice it is desirable tohave the several. valves connected up so that they can be operated by a single lever turned to dittercnt positions. The jar is also connected by means of a. valved connection to an exhausting device, such a vacuum pump; and in this connection isineluded a vacuum measuring device such as a mercury column. l n operation after a tilement has been placed in the clips and the ja closed the jar is exhausted. When this oe' curs the valve between the vacuum producing device and the jar is closed and the eonnection between the jar and the container for the silicon tetrachlorid 1s opened until the mercury drops a certain distance (say six inches). The valve between the silicon tctrachlorid container and the jar is then closed and the other connection admitting the mixture of hydrogen and ethylene gases is then opened and these gases areadmittcd until the mercury in the column has dropped (say fourteen inches) at; which time the valve will he closed and the current turned on which is utilized for {lashing the carbon filament. Oi course in series with the tile ment suitable electrical measuring devices are placed so that when the coiuluctivity of the filan'lent has reached the desired point, the same will be registered and further current can he cut oii and the [lashing stopped.

in preparing the gases for the dashing atmosl'there it is well to see that the hydrogen is tree of oxygen and moisture and the desired mixtirfl: ot hydrogen and ethylene cases is of ethylene gas and 98% of hydrogen.

Having thus described my invention, What I claim is:

The method of manufacturing a carborundum filament which consists in admitting to an evacuated flashing jar a predetermined amount of the vapors ot silicon tetrachlorid then a. predettmnined amount of a mixture of hydrogen and ethylene gases and then in flashing a carbon core in such atmosphere.

In testimony whereof, I. have hereunto suhscriluzd my name this 1st day of DccembCl, 1909.

FRANK (.3. 'll-IOMS.

\Vitnesses ivlax' tiAltItIS, B. F. FUNK. 

